Chap. VI. CONCH 
Of the Ha- the {hell, before opening it, whether it contained any 
bitation of p ear ] f He mentions this to introduce fome fpecula- 
Shells, ^ c ; t ; ons concerning its formation. When no perforation 
or callofity appeared on the outfide, he concluded that 
there was no pearl in the (hell. The pearl-filh, he 
fuppofes, is attacked by two claffes of enemies. One 
is what he calls the auger-worm , which penetrates in- 
to the infide near the edge of the valve, by making a 
longitudinal paffage between the layers of the (hell. 
The length of the channel is one inch, or one inch 
and a half when it doubles back in a line parallel to 
the firft. At the inner extremity there is a fmall cir- 
cular portion, formed by the worm in turning round. 
Thefe excavations are in the pearly part of the (hell. 
The pearly juice, extravafating, forms protuberances 
in the fame direction ; and the cylindrical bodies which 
are thus formed, may be conlidered as elongated pearls 
adhering to the internal furface. When feveral worms 
of this kind unite their labours by penetrating near each 
other, the refult is a kind of pearly wen with irregular 
protuberances. 
Another fea-worm, which he fays belongs to the 
multivalves, a fpecies of pholas, alfo attacks the pearl 
fhells. The Ihell of this fpecies of pholas, has a hinge 
in the form of a crooked bill, as he faw in fome fpe- 
cies of oyfter, which he examined, from the coaft of 
Guinea. The hole was of the (hape of a pear. Pearls 
of this (lrape have been found, and have been held in 
great eftimation. Obferving this circumftance, artifi- 
cial perforations are made in the firell, and this forces 
the animal to produce pearls. In fome fiiells brought 
from China, this artificial hole has been obferved filled 
up with brafs wire, rivetted on the outfide like a nail, 
and the inner extremity of the wire was covered with 
a well-formed pearl, which feemed as if foldered to its 
* Trav. extremity *. 
vol. ii. Pearls are alfo produced by another artificial pro- 
cefs. The fhell is opened with great care to avoid in- 
juring the animal, and a fmall portion of the internal 
furface of the Ihell is fcraped off. In its place is infert- 
OLOGY. 4 7' 7 
ed a fpherical piece of mother-of-pearl, about the fize Of the Ha- 
of a fmall grain of lead Ihot. This ferves as a nU - h’ t ^ t,on of 
cleus, on which is depofited the pearly fluid, and in ^ c 
time forms a pearl. Experiments of this kind have 
been made in Finland, and have been repeated in other 
countries. IJ4 
A remarkable difcovery has been afcribed to Lin- Difcovery 
naeus refpefting the generation of pearls. This was a of Linnseus. 
method which he found out, of putting the pearl-muffel 
(rmja margaritifera) into a ftate of producing pearls at 
his pleafure. It w-as fome years before the final effeft 
could take place ; but, in five or fix years after the 
operation, the pearl, it is faid, had acquired the fize 
of a vetch. But it does not feem to be known in what 
this operation confifted. Whether it confided in imi- 
tating the procefs of infers, by wounding the Ihell 
from the outfide, or by following the other procefs, by 
fcraping away part of the inner layer ; nor is it much 
known what have been the effefts of this operation, or 
whether it has turned to any account, or indeed is at 
all pradlifed in Sweden or any of the northern dates, 
where it mud have been originally known. For this 
difcovery, however, the Swedifli naturalid, it is faid, 
was raifed to the rank of nobility, and otherwife libe- 
rally rewarded by the dates of the kingdom. 
The value which is put on the pearl depends on its 
fize, colour, ffiape, and purity. The larged pearls 
are always held in the highed edimation, when their 
other qualities are in any degree of perfection. The 
fined (hape of the pearl mud be quite globular 5 it 
mud be of a clear brilliant white, fmooth, and gloffy, 
and entirely free from fpot or dain. Pearls were great- 
ly edeemed and much fought after by the Romans, 
Servilia, the mother of Marcus Brutus, we are inform- 
ed, preferded a pearl to Coefar, which was valued at. 
50,000k derling ; and Cleopatra diffolved one, which 
is faid to have been w’orth 250,000k derling, in vine- 
gar, which die drank at a fupper with Mark An- 
tony. 
CHAP. VI. OF THE HABITATION OF TESTACEOUS ANIMALS, METHODS 
OF FISHING, COLLECTING, &c. 
TO the detailed account which we have now given 
of the natural hidory of teflaceous animals, and parti- 
cularly of the formation and growth of the Ihell, we 
have only to add a few obfervations concerning their 
habitation, the methods of fidiing, colledting, and pre- 
ferving them. Thefe topics (hall be the fubjedt of the 
following fedtions. 
Sect. I. Of the Habitation of ’Teflaceous Animals* 
Found on Testaceous animals are found on every part of the 
every part furface of the globe. Some are inhabitants of the land, 
of the while others only frequent rivers and lakes, and a third 
s 0 e ‘ and numerous clafs live in the ocean. From this a claf- 
fification of Ihells has been formed, and they have been 
divided into land, frelh-water, and da fiiells. But 
whatever difference might exid in the habits and eco- 
nomy of tedaceous animals which are produced in 
places fo different, it affords few marks of difcrimina- 
tion for the purpofe of claffification. ^ 
Land Ihells are fpread over the whole furface of the Land fhells 
earth, and although more acceflible, are perhaps lefsvery nume= 
known than thofe which inhabit the ocean. From the roU5, 
fmall number of land Ihells which have been colledled, 
it would appear at firft fight that they are lefs nume- 
rous than marine Ihells. This, however, feems not to 
be the cafe with regard to the number of fpecies 3 and 
it is well known, that the number of individuals of land 
Ihells, in fome inftances, far exceeds that of fea Ihells. 
The fea Ihells of the Mediterranean have been obferved 
by naturalifts, to be nearly the fame from the ftraits of 
Gibraltar to the ifland of Sicily 5 but the land Ihells of 
Languedoc are different from thofe of Provence, of 
Dauphiny, Piedmont, and different parts of Italy- 
Some are found in Spain, in Corfica, in Sardinia and 
Sicily, which are not to be met with in other places j 
and 
